1. Field of the Invention
The present invention relates to a signal splitting apparatus, and more particularly, to a passive signal splitting apparatus.
2. Description of the Related Art
A transmitting and receiving apparatus of a wireless communication system usually comprises a transceiver coupled to an antenna module, wherein the transceiver processes transmitting and receiving signals, and the antenna module transmits and receives signals. If the transceiver comprises a transmitting part and a receiving part, two independent signal propagation paths are required for the transmitting part and the receiving part to prevent signal interference. A conventional transmitting and receiving apparatus may comprise two antennas corresponding to the transmitting part and the receiving part respectively to serve as two independent signal propagation paths. However, the additional antenna increases the size of the transmitting and receiving apparatus, which accordingly increases manufacturing costs and thus does not meet consumers' requirement.
A signal splitting apparatus can be utilized to overcome this problem. FIG. 1 shows a conventional signal splitting apparatus applied to a wireless transmitting and receiving apparatus. As shown in FIG. 1, the signal splitting apparatus 100 comprises a first port 102, a second port 104, a third port 106 and a control port 108. The first port 102 is coupled to an antenna module 110. The second port 104 is coupled to a receiving part 122 of a transceiver 120 via a capacitor 130. The third port 106 is coupled to a transmitting part 124 of the transceiver 120 via a capacitor 140. The control port 108 is coupled to a control port 126 of the transceiver 120 via a control signal line.
When the transceiver 120 is operated in a transmitting mode, the transceiver 120 outputs a switch signal, which propagates through the control signal line, to the signal splitting apparatus 100. Accordingly, the first port 102 is electrically coupled to the second port 104, and the antenna module 110 is coupled to the transmitting part 124. When the transceiver 120 is operated in a receiving mode, the transceiver 120 outputs another switch signal, which propagates through the control signal line, to the signal splitting apparatus 100. Accordingly, the first port 102 is electrically coupled to the third port 106, and the antenna module 110 is coupled to the receiving part 122. By utilizing the signal splitting apparatus 100 shown in FIG. 1, only one antenna is required in the antenna module 110, and accordingly, the manufacturing cost is reduced. However, a control signal line is required between the signal splitting apparatus 100 and the transceiver 120 and thus increases the layout area of the wireless transmitting and receiving apparatus. In addition, the control of the signal splitting apparatus 100 increases the design complexity of the transceiver 120.
Accordingly, there is a need for a signal splitting apparatus, which can replace conventional signal splitting apparatuses without the additional control signal line, and exhibits the advantage of low manufacturing cost.